Voltage regulating apparatus



"Au 1, 1933. C. H. ZlERDT 1,920,618

VOLTAGE REGULATI NG APPARATUS Original Filed 001. 12, 1928 INVENTOR. QZ. Iii Z1? awn/M l w ATTORNEY.

Patented Au yl, 193:.v

UNITED srA rss PATENT"! OFFICE legheny County, Pa.,

assignor to The Union Switch & Signal Company, Swissvale,-Pa., aCorporation of Pennsylvania Original application October 12, 1928,Serial No. 312,048. Divided and this application October 25, 1930.Serial No. 491.197

1 Claim. (01. 171-119 My invention relates to voltage regulatingapparatus, that is, apparatus for use between a source of energy and anenergy consuming device for regulating the voltage applied to said 5device.

' The present application is a division oimy copending application filedOct. 12, 1928, Serial No. 312,048, for Voltage regulating apparatus.

1' will describe two forms of apparatus embodyingmy invention, and willthen point out the novel features thereof in the claim.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing oneform of voltage regulating apparatus embodying my invention applied to astorage battery charging circuit. Fig. 2'is adiagrammatic view showing amodified form of voltage regulating apparatus also embodying myinvention.

Similar reference characters refer to similar parts in each of theviews.

Referring first to Fig. 1, the reference character 'I designates atransformer, the primary it of which is connected with a suitable sourceof alternating current here shown as an alternator G. The secondary 15of transformer T is connected, through a current limiting impedance A,with the input terminals 7 and 7 of a rectifier R comprising a pluralityof asymmetric units 9 connected in the usual manner to pro- 39 vide fullwave rectification. The output terminals 8 and 8*- of rectifier R areconnected through a switch F with a storage battery C which is to becharged by the unidirectional current delivered by the rectifier.

With the apparatus constructed in the manner thus far described, undernormal conditions, that is, when switch F is closed, current from thesecondary 15 of transformer T is supplied to battery C through rectifierR, and the 40 parts are so proportioned that this current upon flowingthrough the impedance A creates a potential drop in the impedance whichmaintains the voltage impressed across the input terminals 7 and '7 ofrectifier R. at a value which is slightly higher than the terminalvoltage of storage battery C. The impedance A is so constructed that itsfiux density in response to this normal current, is comparatively low.The reactance of A is therefore substantially constant through a widerange of variations in the current. If, now, switch F is opened, thecurrent flowing in impedance A is greatly diminished, so that thepotential drop across the impedance is also greatly diminished, and ifthe voltage of the secondary 15 of transformer '1 is constant, thevoltage impressed across the input terminals of rectifier R rises. Thisrise in voltage in some instances, may be sumciently great to damage therectifier R. To prevent this undesirable rise in voltage, 1 provide areactor 00 B comprising a closed iron core 6 carrying a primary winding3 and a secondary winding 4. The terminals 12 and 1 3 of the primarywinding 3 of reactor B are connected with the input terminals '7 and "i,respectively of rectifier R. An asymmetric unit 5 is connected directlyacross the secondary winding 4 of reactor B.

It is apparent that the voltage impressed across input terminals 7' and7 of rectifier R is also impressed across terminals 12 and 13 of winding3 of reactor B. An alternating current therefore flows in winding 8, andan alternating flux is set up in core 6. This alternating flux in core 6tends to induce an alternating electromotive force in winding l ofreactor B, but since asymmetric unit 5 is connected in series withwinding 4, a unidirectional current flows in winding 4 which creates anunidirectional flux in core 6 in' addition to the alternating fluxvcreated in core 6 by the alternating current in 30 winding 3. The partsof reactor B are so proportioned that under normal conditions, that is,when switch F is closed, the flux density in the core 6 is nearsaturation. It, now, the voltage impressed upon rectifier R tends torise for any reason, such as the opening of switch F, the currentflowing in winding 3 of reactor B increases, so that the flux density incore 6 increases, and the impedance of winding 3 therefore decreases.Since winding 4 and rectifier 5 cooperate to create a unidirectionalflux in core 6, as has already been described, the decrease in impedanceof winding 3 due to a given rise in the voltage applied to its terminalsis greater than would be thecase if winding 4.and rectifier 5 wereomitted. As a result of this decrease in the impedance of winding 3, thecurrent I through the winding is still further increased. But theincreased current in winding 3 causes 10') an increase in the potentialdrop across impedance A, with the final result that the voltage appliedto terminals '7 and '7? 01' rectifier B when switch F is opened isconsiderably smaller than would beuthe case if reactor B were not 105provided. By properly designing the reactor B and the impedance A, thevoltage across the terminals of rectifier R may be made substantiallyconstant. p

In the modification shown in Fig. 2, an asymno metric unit 18 isconnected in series with the winding 3'of an iron core reactor K so thatthe current flowing in winding 3 is unidirectional I reactor constructedin this manner, since the fiux in core 6 is a unidirectional flux, thedecrease in impedance in winding 3 for a given rise in voltage atterminals 12 and 13 is considerably greater than the decrease inimpedance in the winding of a similar reactor not having the asymmetricunit in series with the winding. This effect may further be increasedvby using an asymmetric unit 18 of the type com.- prising a copper diskhaving a coating of cuprous oxide formed on one side thereof. A unit ofthis type exhibits the characteristics of decreasing its resistance withincreases in the electromotive force applied across the unit. Theapparatus of Fig. 2, as a whole, functions in the manner previouslydescribed in connection with Fig. 1.

- 1,920,618 a v a Although I have'herein shown and described only twoforms of voltage regulating apparatus embodying my invention,- it isunderstood that various changes and modifications may be made thereinwithin the scope of the appended claim without departing from the spiritand scope of my invention. y

Having thus described my invention, what I claim is: v

Voltage regulating apparatus for use with a source of alternatingcurrent connected with a load and an impedance interposed between-thetwo, comprising, in combination with the fore-' going elements, areactor having an iron core provided with only a single winding thewhole of which is connected in multiple with said load,

and an asymmetric unit of the copper oxide type included .in series withsaid windings, the parts of said apparatus being so proportioned thatwhen normal voltage is applied to the load the flux density in said coreis near saturation.

CONRAD H. ZIERDT.

